Assimilator

Assimilator

Pinewood Derby Times
Volume 11, Issue 2
October 19, 2011

In this Edition:

- Editor's Notes

- Feature Article - Shop Talk: Drilling Small Holes

- Humor

- Product Showcase - Cobalt Split Point #44 Bits: Over 20% Off

- Pinewood Derby Car Showcase

- Q&A


Editor's Notes

Reader Feedback
We received quite a bit of feedback on the article entitled "Do's and Don'ts for Race Leaders" in Volume 11, Issue 1. Here are a few:

"I read your article on the complaints you received from some parents stating that they bought wheels from your web site, and that when they went to a district meet, they were disqualified. As a member of our District Pinewood Derby race committee, I felt compelled to write to you. I am like most of your readers, we get a list of rules that are at best, very vague. At a District Derby a couple of years ago, I heard several parents complain that the rules were too vague, open to interpretation, and that there was no set guidelines. We formed a team of what we called Pinewood Derby Experts. We sat down and hashed out the rules; quite simply, we made a statement that the wheels must say BSA Pinewood Derby on them, they are not to be narrowed and can be lathed as long as there was evidence that the little tire tread marks on the side where still visible. We also stated that they can be colored, as long as BSA Pinewood Derby was on the sidewall. We also condensed the rules to a simple two page attachment that was sent out three months before the derby so that any rule in question could be discussed at a District Roundtable with all the Cubmasters involved. A truly well run plan can and will always have something that can be misread or misunderstood. At last year's District Derby, we had no disqualified cars, all wheels were BSA, and the race rules were well liked. We are planning on using these rules again for this year's Derby. I know this will not help other Districts with their rules, but our District has had and hopefully, will continue with its success. As always, thanks for the service you provide. I always tell my Cub Scout Packs to go to your web site for useful tips and car ideas; you make my job easier."
Name withheld upon request

"In regards to issues with the race rules, I think this is a case of someone being overzealous for some cars and not others. Common sense would say that since they had so many cars being disqualified someone on the race committee should have stepped forward and either questioned the officials, asked for an Outlaw race for those that did not pass inspection, or at the very least re-inspect those cars in question -- remembering that these racers traveled in hopes of competing.

We have for several years sent with our Pack the rules that are prepared by the District committee, and we run our races with the same rules in hopes to eliminate the disqualification of any cars at the district level. As a long time Scout Leader the rules can be rigorous, and are always changing slightly due to fairness and vendors like Maximum Velocity providing parts on the cutting edge; but if you explain and go through the rules and expectations with your scouts, adults and other leaders, they are easily followed. As leaders we need to be advocates for fairness and this can be as simple as adding some sort of Outlaw race to allow for these situations.

In our district race and our Pack race we use non-scout adults at the registration tables to help ward off any competition bias. We teach them the rules and what and how to look for violations. I firmly believe that those bringing cars need to bring extra of everything so they can, if allowed, be able to switch out parts to pass inspection. In the case of weight just the air temperature and the difference in a scale brand can provide for overweight issues.

In our races we give every racer as much leeway and help in the pit area as possible to let them race; we supply some extra wheels, axles, weight options and tools for the scouts to adjust their cars to make inspection."
Keith Larson
Cub Master Pack 53 Bagley, Minnesota
Race Director/District Race Official
Two-Wheeled Car Results
In Volume 10, Issue 14, the article "Two-Wheeled Cars Revisited" mentioned that the car would be raced in April and that I would report back to you in the fall.
The car ran very smoothly, easily beating all but two cars (which were equipped with needle axle outlaw wheels, one of which I built). The car also received the positive crowd response that I was hoping for.

But in the third heat, the front "spoiler" broke off in the stop section. I didn't notice the missing part until I was staging the car for the final race. Our rules state that the only broken car part that can be replaced is a wheel, so nothing could be done. Since the spoiler was needed to trip the finish line, the car got a DNF (did not finish) for the final heat and ended up taking fourth place. I could have argued that the car did finish; the problem was that the sensor didn't detect it. But since I was the race leader, I didn't think that was appropriate. Obviously, the spoiler needs to be mechanically reinforced, as opposed to just attached with glue.

Inventory Clearance Sale
We currently have all of our printed Car Plans booklets, several kits, and other items on sale. Click Here to find our clearance items. Don't miss out on the great prices.

Can We Help?
If we can help you in any way with your pinewood derby project, or if you have any feedback regarding this newsletter, please contact us at: info@maximum-velocity.com


Feature Article

Shop Talk: Drilling Small Holes
By Randy Davis

If your pinewood derby race rules allow axle holes, then you have likely drilled the holes using a drill press, or a Pro-Body Tool or Pro-Axle Jig1 from Derby Worx. For Cub Scout axles, a #44 bit2 is recommended, while a 3/32 inch bit is typically used for Awana axles. For a few other kits, a #43 bit works well. But regardless of the bit size, have you considered the best type of bit to use? The type of bit, as well as the technique used, both affect the accuracy of the result. In today's shop talk we will discuss the various types of drill bits and some techniques to help improve accuracy.

Small Drill Bit Types
The most common small drill bit types are high-speed steel (HSS), carbide, and cobalt.

HSS
HSS drill bits are flexible and strong.3 They are inexpensive and used where long-term durability is not important. Most drill sets are HSS. The flexibility of the HSS bit is helpful in minimizing broken bits, but the flexibility is a hindrance where accuracy is concerned. For drilling axle holes with a Pro-Body Tool/Jig, a HSS bit is fine, as the tool minimizes the flexing of the bit; but when drilling holes with a drill press the flexibility really hinders accuracy.

Carbide
Carbide drill bits are extremely hard, so flexing is virtually eliminated. However, because they do not flex, they are prone to breakage if careful technique is not applied. Carbide bits often come with a shank larger than the bit. So if you purchase one, make sure to get one that is long enough to drill axle holes - many Carbide bits are too short for drilling axle holes.


Figure 1: Typical Carbide Bit
(Source: www.carbidespecialties.com)

Cobalt
Cobalt bits4 are also extremely hard, so flexing is virtually non- existent. But Cobalt bits have a big advantage over HSS and Carbide bits -- Cobalt bits have a "split point" tip that is specifically designed to keep the bit from "wandering" (i.e., not entering the wood at the location you want).

Wood is a relatively soft medium, but it is not consistent in density. Depending on the grain, wood will change from a hard to soft density over a small fraction of an inch. This change in density affects the way the drill bit goes into the wood. The drill bit will seek to go into the softer part of the wood. With a HSS bit, the bit may wander seeking a soft spot, and then when it has entered the wood it will tend to flex away from the hard grain. This results in inaccurate holes. Carbide bits also wander, and if they wander when in a drill press, due to the rigidity of the bit either the wood will move, or the bit will break. It seems odd, but I have broken more carbide bits when drilling into wood than any other type of bit.

Cobalt bits, with their split point, are virtually wander-free. Like other bits, once the bit enters the wood it will want to follow the softer grain, but this can be compensated for with proper drilling technique.


Figure 2: Cobalt Split Point vs. Typical Bit

Drilling Technique
When drilling into wood, there are three techniques that greatly improve accuracy. First, expose only the amount of the bit needed to drill the hole -- leave the rest inside the drill chuck. This minimizes the opportunity of the bit to flex (or break). Second, run the drill at full speed (1,500 rpm on a drill press)15, but enter the wood slowly. This helps to make a clean entry hole, and minimizes drill bit wander and flexing. Next, drill about half way in, pull the bit out enough to clear the debris from the drill bit flutes, and then finish the hole. The pine sap limits the ability of the flutes to clear the debris. If you don't clear it, it can jam up, resulting in an inaccurate hole and/or an overheated bit.

Pro-Body Tool
When drilling holes with a Pro-Body Tool/Jig, make sure the tool is clamped tightly to the block and the block is clamped in place. Then, making sure that the bit is parallel to the hole in the tool, spin the drill up to speed and enter the wood slowly. Drill about halfway in, pull the drill bit back to clear the flutes, and then complete the hole.

Drill Press
When using a Drill Press, use an accurate fence to stabilize the block and set the offsite from the bottom of the block. Squeeze (or clamp) the block to the fence, then enter the wood slowly, clear the flutes at the half-way point, then complete the hole.

Final Thoughts
Drilling accurate axle holes is a challenge which can be greatly simplified by using the right equipment. When selecting equipment, the type of drill bit is one decision you don't want to overlook.

1While there are other drilling guide products available, these two Derby Worx tools are the most popular tools on the market today. You can find them Here.

2Drill bits are available in four size classifications. The first class, the type in most people's tool box, is "fractional" (1/16, 3/32, 1/4, etc). The second size class (most popular outside the US) is "metric" (1mm, 2mm, 3mm, etc). The third class is "numbered". Numbered bits have very small increments and range from "80" (.0135 inches) to "1" (.228 inches). The #44 drill bit used for Cub Scout axles is 0.086, which is about halfway between the 5/64 and 3/32 inch fractional bits. The final drill bit class is "letter". These bits start after the number "1" bit and range from "A" (.234) to "Z" (.413)

3We have our remaining HSS #44 bits on sale Here.

4Beginning in October 2011, the #44 bits sold by Maximum Velocity are Cobalt Split-Point drill bits. They are on sale for the next two weeks Here.

5For Dremel type tools, run on a low to medium speed.



Humor

A man is driving his pickup down a country lane when suddenly a chicken darts out into the road in front of him. He's just about to slam on his brakes to avoid the chicken when he realizes that the chicken has sped on ahead, doing about 30 miles per hour.

Amazed, he speeds up to follow, but the chicken takes off faster and faster. Finally the chicken screeches into a turn and goes into a small farm.

As he turns to follow, the guy notices that the chicken has three legs. He pulls to a stop in front of the farmhouse, and looking around, notices that ALL the chickens have three legs.

He says to the farmer; "Three-legged chickens? That's astounding!"

The farmer replies; "Yep, I bred 'em that way. I love drumsticks."

"Well, tell me," asks the guy "how does a three-legged chicken taste?"

"Dunno," says the farmer "I haven't been able to catch one yet."



Product Showcase

    Cobalt Split Point #44 Bits    
Over 20% off

The #44 drill bit (.086 inch OD) is the standard bit used for nail axles from Cub Scout kits and other kits. It can be used to drill axle holes, or to create pilot holes in the standard axle slots. Unlike most drill bits (high-speed steel, 118 degree cutting angle, and non- split point), our drill bits are made of cobalt (a much harder metal) to minimize bit flexing. In addition, the cutting tip is 135 degrees and is ground into a split-point configuration. The 135 degree split- point provides more cutting surface right at the start of the hole, so that drill bit wandering is virtually eliminated.

Through November 1, 2011, you can get these bits for over 20% off. To take advantage of this limited time offer, Click Here.



Car Showcase

Space Buggy & Flash of Night - Jim White

My grandson (Aaron Shain) and I built these two cars for his 2011 racing campaign. I hope Aaron's hard work pays-off at the finish line.

American Flag & Ben 10 - Scott Moran

My oldest boy (Shane - 11 years old) designed the American Flag car. My youngest boy (Matthew - 8 years old) designed the Ben 10 car. Shane took 1st and Matthew took 2nd in their pack. The boys cut their cars, sanded the body, applied the wood putty, and primed and painted the cars with my airbrush equipment (the high shine comes from using PPG Deltron basecoat clearcoat). I could go on and on about the paint jobs because they did an awesome job. I have been custom painting and airbrushing for 25 years and my wife and I taught the kids to write their names with an airbrush.

Midnight - Lee Klinghoffer

This is my first foray into Pinewood Derby car-building since I was 11 -- now I'm 48. I entered this in my son's pack race in the "Open" category. It weighed in at 16.1 ounces! Everything else is stock except for the homemade speed axles. I cut 2 v-shaped grooves in them and polished to a high sheen. The car took 1st Place and a new track record.

Share your car with our readers!

Do you have a car you would like to 'show off' to our readers? If so, send us a photo of your car along with a brief description of any special features. Also, please include your full name. If selected, we will include the photo and description in this newsletter.Please e-mail photos to:
info@maximum-velocity.com.

Photos must be sent by e-mail in JPG format (minimum size of 640x480, maximum size of 1280 x 960). Please shoot photos from the front left of the car, similar to the orientation of this car:


Send only one photo per car, unless an additional photo is needed to adequately show a feature. Also, only one car per subscriber per year please. Thanks!



Pinewood Derby Memory

Help! We are out of Pinewood Derby memories, but I am sure that our readers have many memories to share. Please jot down your humorous, unusual, sad, or heart-warming pinewood derby tale and send it to: info@maximum-velocity.com

If your memory is used, you will receive a $10 coupon in May of 2011.

Don't worry about literary polish. We will edit as needed. Also, please read our Submission Policy



Q&A

Our pack track was apparently purchased about 10 or 12 years ago and is made of plywood. It's very nice, smooth and fits together very well. But the braking section is totally inadequate (cars get damaged). Do you know of anybody (or maybe your company) that could put together a real nice braking system for this track?

I don't believe you could find an off the shelf braking system, since your track is likely a custom size, but it should be fairly easy to make a braking section. Usually it is 4 feet long, with guide rails 2 to 3 times taller than the standard rails. The section is setup so that the top of the braking section rails are evenly aligned with the top of the regular rail. So when the car enters the braking section the car's belly drops onto the raised rail. A rubber strip is attached to the top of the braking section rail, so the cars stop quickly. It would be similar to this one for the BestTrack aluminum track

You just have to make sure that the braking section rails are spaced exactly the same as on the final section of the track.

We were wondering if you've ever done an analysis of how much distance in inches that a difference in time equals (on a 32 foot track). For example, if one time is 2.5200 and the next is 2.521, what would that be in inches?

The problem with making the calculation is that the car is not maintaining a steady speed over the full course. You can make an estimate assuming the speed is constant, but it will be overstated because the car is slowing down at the finish line.

The 2.5 second times you are quoting are similar to the times on my aluminum track. The actual length of my track in inches is 355.5. So if the track is covered in 2.520 seconds, then the car is traveling at a rate of 0.141 in/msec. Thus, it crosses the finish line about 0.141 inches ahead of a car that finishes in 2.521 second. This is just over 1/8 inch. However, in reality the car is going slower. So the difference in inches is less -- probably 1/16 inch.

Do You Have Questions that Need Answers?
Do you have a pinewood derby-related question? If so, send your question to: info@maximum-velocity.com. We answer all questions by e-mail, but not every question will appear in the Q&A section of the newsletter.



Back Issues

Are you a new subscriber, or have you missed some of the previous newsletters? Don't miss out! All of the issues for Volume 5 through Volume 9 are posted on our web site and can be found using our Newsletter Index.

Issues from Volumes 1 to 4 are available in four formatted documents, ready for immediate download. To find out more, Click Here.




Newsletter Contributions

We welcome your contributions! If you would like to contribute an article, a web site review, or a speed tip, please send it to: info@maximum-velocity.com.

Please read our submission policy.



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The Pinewood Derby Times is a free e-newsletter focused on the Pinewood Derby. It is published bi-weekly from October through April.

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Randy Davis, Editor, Pinewood Derby Times
E-Mail: info@maximum-velocity.com


Copyright ©2011, Randy Davis. All rights reserved. Please do not reprint or place this newsletter on your web site without explicit permission. However, if you like this newsletter we grant permission, and encourage you to e-mail it to a friend.

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